Statements using the class are explicit conversions.
a. explicit
b. convert
c. explicitconvert
d. converttype

Explicit

Explanation:

 The statement which used the explicit class are the explicit conversion, as  it is type of the conversion which uses the conversion keyword. These type of the keywords act as a function in the explicit conversion and compiler generating the code in the given inline function.  

Explicit conversion basically require the cast operator in its function when, the information is lost during explicit conversion.

Conversion of base class into the derives class is one of the typical example of the explicit conversion.